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Image enhancement using alpha rooting based hybrid technique
The document proposes a hybrid technique for image enhancement combining alpha rooting, log transformation, and power law transformation. Alpha rooting is applied in the frequency domain to separate magnitude and phase coefficients, enhancing sharpness but darkening the image. The proposed method applies log and power law transforms after inverse transformation to eliminate tonal changes and improve contrast and brightness. Experimental results demonstrate the hybrid approach enhances images while avoiding darkening artifacts of conventional alpha rooting. In conclusion, the alpha rooting based hybrid technique provides image enhancement without limitations of prior transform domain methods.
Image enhancement using alpha rooting based hybrid technique
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- 3. Image Enhancement inSpatial domain
- 4. Gray Level TransformationFunctions
- 5. Gray Level TransformationFunctions
- 6. Negative Image Transformation s= 1 - r s = 1 – r where, s = output image gray level r = input image gray level
- 7. Log transformation s =c log ( 1 + r ) where, c = scaling factor
- 8. Power law transformationfunction
- 9. Power law transformationfunction
- 10. Power law transformationfunction
- 11. Power law transformationfunction
- 12. By Alpha Rooting ImageEnhancement in Frequency domain Orthogonal transformation
- 13. Image |X(p,s)| Magnitude (contains frequency content ofimage) θ(p,s) Phase (angle of the magnitude content) Orthogonal transform X(p,s) = |X(p,s)| e jθ(p,s) Orthogonal transformation Inverse Orthogonal transform Enhanced Image Operation Separation Combination
- 14. Alpha Rooting X(p,s) =|X(p,s)| e jθ(p,s)α^ • Operation in orthogonal transformation, where, 0 < α < 1 • here, X(p,s) is alpha rooted image ^ (a) (b)
- 15. Alpha Rooting BasedEnhancement Procedure Conventional Alpha Rooting results in • Subtle edge information in images • Increases sharpness • Makes image crisper Enhancement in sharpness is mostly subdued by overall darkening of image which is artifact of alpha rooting Requirements • Eliminate Tonal change • Achieve good contrast and brightness Remedy • Apply log transform • Apply power law transform
- 16. Proposed Method Input Image Apply Orthogonal Transformation SeparateMagnitude and phase coefficients X(p,s) = |X(p,s)| e jθ(p,s) Apply Alpha Rooting on magnitude |X(p,s)|α Combine Magnitude and phase components Inverse Orthogonal Transform Apply Log Transformation s = c log(1+r) Apply Power Law Transformation s = b rγ Enhanced Image
- 17. Experimental Results (a) (b) (c)(d) Fig (a) : Original Image Fig (b) : Alpha Rooted using α = 0.72 Fig (c) : Hybrid Alpha Rooted using α = 0.78, b = 1.2, γ = 0.8 Fig (d) : Hybrid Alpha Rooted using α = 0.7, b = 1.2, γ = 0.8
- 18. Experimental Results Fig (a): Original Image Fig (b) : Alpha Rooted using α = 0.78 Fig (c) : Hybrid Alpha Rooted using α = 0.75, b = 1.1, γ = 2 (a) (b) (c)
- 19. CONCLUSION In this paperwe elucidated an Alpha Rooting Based Hybrid Procedure for image enhancement which is free of the conventional limitations associated with the transform domain image enhancement techniques.
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